The prevalence of mental disorder amongst prisoners refusing food was studied by examining the prison records of a remand prison and a dispersal prison. Food refusal occurred predominantly in the remand prison. Less than one per cent of the annual remand population engaged in this behaviour. The results indicate that prisoners refusing food do so as a form of protest and that the prevalence of mental disorder among such prisoners is high. The majority respond to observation and counselling. Important indicators of psychosis are: (i) the inability of the prisoner to divulge reasons for his behaviour; and (ii) the refusal by the prisoner of both food and fluids. In such cases transfer to hospital for treatment may be urgently required.